Wrinkled nanoporous gold films with ultrahigh surface-enhanced Raman scattering enhancement.
ABSTRACT Amplified by plasomonic nanostructured metals, Raman intensity of organic molecules and biomolecules can be dramatically improved, particularly at "hot spots" where intense electromagnetic fields are produced in the vicinity of narrow nanogaps between metallic nanostructures. Therefore, developing new substrates with a high density of "hot spots" has been the recent topic of intense study. Here we report wrinkled nanoporous gold films that contain abundant Raman-active nanogaps produced by deformation and fracture of nanowire-like gold ligaments. This novel nanostructure yields ultrahigh surface enhanced Raman scattering for molecule detection.
Article: Ultrasensitive optofluidic surface-enhanced Raman scattering detection with flow-through multihole capillaries.[show abstract] [hide abstract]
ABSTRACT: 3-Dimensional surface-enhanced Raman scattering (SERS) detection integrated with optofluidics offers many advantages over conventional SERS conducted under planar and static conditions. In this paper, we developed a novel optofluidic SERS platform based on nanoparticle-functionalized flow-through multihole capillaries for rapid, reliable, and ultrasensitive analyte detection. The unique configuration not only provides 3-dimensional geometry for significantly increased SERS-active area and inherent fluidic channels for rapid and efficient sample delivery, but also confines and transmits light along the capillary for large SERS signal accumulation. Using a capillary consisting of thousands of micrometer-sized holes adsorbed with gold nanoparticles, we investigated the proposed optofluidic SERS system using the transverse and longitudinal detection methods, where the SERS excitation and collection were perpendicular to and along the capillary, respectively. A detection limit better than 100 fM for rhodamine 6G was achieved with an enhancement factor exceeding 10(8).ACS Nano 12/2011; 6(1):381-8. · 10.77 Impact Factor
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ABSTRACT: Detecting and identifying single molecules are the ultimate goal of analytic sensitivity. Single molecule detection by surface-enhanced Raman scattering (SM-SERS) depends predominantly on SERS-active metal substrates that are usually colloidal silver fractal clusters. However, the high chemical reactivity of silver and the low reproducibility of its complicated synthesis with fractal clusters have been serious obstacles to practical applications of SERS, particularly for probing single biomolecules in extensive physiological environments. Here we report a large-scale, free standing and chemically stable SERS substrate for both resonant and nonresonant single molecule detection. Our robust substrate is made from wrinkled nanoporous Au₇₉Ag₂₁ films that contain a high number of electromagnetic "hot spots" with a local SERS enhancement larger than 10⁹. This biocompatible gold-based SERS substrate with superior reproducibility, excellent chemical stability and facile synthesis promises to be an ideal candidate for a wide range of applications in life science and environment protection.Scientific Reports 01/2011; 1:112.